Slider having adjusted transducer recession and method of adjusting recession

ABSTRACT

A method and apparatus are provided for adjusting recession of an element, such as a pole tip, in a transducer structure formed in a plurality of thin film layers on an edge of a slider. A pre-stressed structure is formed as part of the plurality of thin film layers on the edge of the slider. The pre-stressed structure has a level of material stress. The recession is measured relative to a bearing surface of the slider, and then the level of material stress is adjusted as a function of the measured to effect a corresponding change in the recession.

FIELD OF THE INVENTION

The present invention relates to data storage systems and, moreparticularly, to a slider and a method of fabricating a slider having abearing surface and a transducer structure with an element, such as apole tip, which has a desired recession relative to the bearing surface.

BACKGROUND OF THE INVENTION

Data storage systems use magnetic or other media for storage of digitalinformation. For example, typical disc drives use rigid or flexiblediscs coated with a magnetizable medium for storing information in aplurality of circular, concentric data tracks. The discs are mounted ona spindle motor, which causes the discs to spin and the surfaces of thediscs to pass under respective hydrodynamic (e.g., air) bearing dischead sliders. The sliders carry transducers, which write information toand/or read information from the disc surface. An actuator mechanismmoves the sliders from track to track across the surfaces of the discsunder control of electronic circuitry. The actuator mechanism includes asuspension for each slider. The suspension includes a load beam and agimbal. The load beam provides a load force, which forces the slidertoward the disc surface. The gimbal is positioned between the slider andthe load beam, or is integrated in the load beam, to provide a resilientconnection that allows the slider to pitch and roll while following thetopography of the disc.

The slider includes a slider body having a bearing surface, such as anair bearing surface, which faces the disc surface. As the disc rotates,the air pressure between the disc and the air bearing surface increasesand creates a hydrodynamic lifting force, which causes the slider tolift and fly above the disc surface. The preload force supplied by theload beam counteracts the hydrodynamic lifting force. The preload forceand the hydrodynamic lifting force reach an equilibrium, whichdetermines the flying height of the slider relative to the disc surface.

In some applications, the slider flies in close proximity to the surfaceof the disc. This type of slider is known as a “pseudo-contact” slider,since the bearing surface of the slider can occasionally contact thesurface roughness of the disc. In other applications, the slider isdesigned to remain in direct contact with the disc surface withsubstantially no air bearing. These sliders are referred to as “contactrecording” sliders. The transducer is typically mounted at or near thetrailing edge of the slider so that it is located near the closest pointon the slider body to the media.

A thin film type of transducer is a microstructure that is designed toperform certain electric, electromagnetic or optical functions duringreading and/or writing. Thin film transducers are typically fabricatedin an array on an active surface of a wafer substrate through a seriesof material deposition, etching and liftoff process steps. The wafersubstrate is typically made of a ceramic material. Once the array oftransducers has been fabricated, the wafer substrate is divided into anumber of individual slider bodies. Each slider is thus composed of aceramic body and a thin film transducer on one side of the body.

During operation, the distance between the active element of thetransducer structure, such as the pole tips in a magnetic writetransducer, and the media is known as the “head-media spacing”. As therecording densities of data storage systems continue to increase, it isimportant to maintain a substantially constant head-media spacing duringoperation and to have tight control over the head-media spacing from oneslider to the next during fabrication.

In addition to the flying characteristics of the slider, the head-mediaspacing depends on the vertical position of the pole tip (or otheractive element) on the slider body. Two primary factors contribute tothe pole tip position. The first is pole tip recession (PTR), in whichthe vertical position of the pole tip becomes recessed relative to thebearing surface due to the machining and other fabrication processes ofthe slider and transducer structures. The second is thermal pole tipprotrusion (TPTP), which is caused by increases in the environmentaltemperature of the product and by heat generated by the write currentthrough the transducer during normal operation. Manufacturing variationsin pole tip recession therefore contribute to undesirable variations inhead-media spacing, which can limit recording density.

The present invention provides a solution to this and other problems andoffers other advantages over the prior art.

SUMMARY OF THE INVENTION

One embodiment of the present invention is directed to a method ofadjusting recession of an element in a transducer structure, which isformed in a plurality of thin film layers on an edge of a slider. Themethod includes: (a) forming a pre-stressed structure as part of theplurality of thin film layers on the edge of the slider, which has alevel of material stress; (b) measuring the recession relative to abearing surface of the slider; and (c) adjusting the level of materialstress as a function of the recession measured in (b) to effect acorresponding change in the recession.

Another embodiment is directed to a method of adjusting recession of anelement in a transducer structure formed in a plurality of thin filmlayers on an edge of a slider. The method includes: (a) forming apre-stressed structure as part of the plurality of thin film layers onthe edge of the slider, wherein the pre-stressed structure comprises amaterial having a different thermal coefficient of expansion than anadjacent one of the plurality of thin film layers, which is in contactwith the pre-stressed structure, such that the material has a level ofmaterial stress; (b) measuring the recession relative to a bearingsurface of the slider; and (c) adjusting the level of material stress asa function of the recession measured in (b) to effect a correspondingchange in the recession.

Another embodiment is directed to a slider, which includes a sliderbody, a transducer structure and a position adjustment structure. Theslider body has a bearing surface, a back surface, which is opposite tothe bearing surface and an edge, which extends between the bearingsurface and the back surface. The transducer structure is formed in aplurality of thin film layers on the edge of the slider and has anelement with a vertical position relative to the bearing surface. Theposition adjustment structure is formed as part of the plurality of thinfilm layers and includes a material having a different thermalcoefficient of expansion than an adjacent one of the plurality of thinfilm layers, which is in contact with the position adjustment structure,such that the material has a level of material stress. The positionadjustment structure has a material stress adjustment pattern that is afunction of the vertical position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a disc drive with which one embodimentof the present invention is useful.

FIG. 2 is a perspective view of a typical wafer for fabricating aplurality of slider bodies.

FIG. 3 is fragmentary, perspective view of a bar of slider bodies slicedfrom the wafer shown in FIG. 2.

FIG. 4 schematically illustrates pole tip recession and head-mediaspacing for one of the sliders relative to a bearing surface on theslider.

FIG. 5 is a fragmentary, trailing end view of the slider, whichillustrates the addition of a pre-stressed structure along a trailingsurface of the slider, according to one embodiment of the presentinvention.

FIG. 6 is a cross-sectional view of the slider taken along lines 6-6 ofFIG. 5.

FIG. 7 is a diagram of an apparatus for adjusting the recession of thepole tip (or other active element) of a transducer toward a desiredvertical position, according to one embodiment of the present invention.

FIG. 8 is a flow chart illustrating a sequence of steps for adjustingrecession of the pole tip (or other active element) of the transduceraccording to one embodiment of the present invention.

FIG. 9 is a graph illustrating the deformed shapes along the bearingsurface of the slider for various materials used for the pre-stressedstructure following a simulated laser heat treatment.

FIG. 10 is a chart illustrating normalized pole tip recession responsedue to the simulated laser heat treatment for the various materialsshown in FIG. 9.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 is a perspective view of a disc drive 100 with which oneembodiment of the present invention is useful. Disc drive 100 can beconfigured as a traditional magnetic disc drive, a magneto-optical discdrive or an optical disc drive, for example. The present invention isalso useful in other types of systems in which a transducer is supportedby a substrate relative to a medium with which the transducercommunicates.

Disc drive 100 includes a housing with a base 102 and a top cover (notshown). Disc drive 100 further includes a disc pack 106, which ismounted on a spindle motor (not shown) by a disc clamp 108. Disc pack106 includes a plurality of individual discs 107, which are mounted forco-rotation about central axis 109. Each disc surface has an associatedslider 110, which is mounted to disc drive 100 and carries a read and/orwrite transducer for communication with the disc surface.

In the example shown in FIG. 1, sliders 110 are supported by suspensions112 which are in turn attached to track accessing arms 114 of anactuator 116. The actuator shown in FIG. 1 is of the type known as arotary moving coil actuator and includes a voice coil motor (VCM), showngenerally at 118. Voice coil motor 118 rotates actuator 116 with itsattached sliders 110 about a pivot shaft 120 to position sliders 110over a desired data track along a path 122 between a disc inner diameter124 and a disc outer diameter 126. Voice coil motor 118 operates undercontrol of internal circuitry 128. Other types of actuators can also beused, such as linear actuators.

During operation, as discs 107 rotate, the discs drag air (or otherfluid) under the respective sliders 110 and along their bearing surfacesin a direction approximately parallel to the tangential velocity of thediscs. As the air (or other fluid) passes beneath the bearing surfaces,fluid compression along the flow path causes the fluid pressure betweenthe discs and the bearing surfaces to increase, which creates ahydrodynamic lifting force that counteracts the load force provided bysuspensions 112 and causes the sliders 110 to lift and fly above or inclose proximity to the disc surfaces.

Sliders 110 are formed from a substrate, known as a wafer. FIG. 2 is aperspective view of a typical wafer 200. Wafer 200 can include ceramic,aluminum oxide titanium carbide, aluminum silicon magnesium or silicon,for example. Other materials can also be used. Wafer 200 has an activesurface 202 on which a matrix of transducers 204 (shown schematically)are fabricated through a series of thin film material deposition,etching and liftoff process steps. Wafer 200 is then sliced along lines206 into a plurality of bars 208. Each bar 208 includes a plurality ofindividual slider bodies, with each body having a correspondingtransducer structure.

FIG. 3 is fragmentary, perspective view of a bar 208 of slider bodiessliced from wafer 200. Each bar 208 includes a plurality of individualslider bodies 110, with each slider body 110 having a correspondingtransducer 210. For each slider body 110, the sliced surfaces of wafer200 become a bearing surface 220 and a back surface 222. The activesurface 202 and the back surface 203 of wafer 200 become a trailingsurface 224 and a leading surface 226, respectively, of the slider body.

Once wafer 200 has been sliced into individual bars 208, the bar islapped to obtain a target throat height for each transducer (in the caseof a magnetic type of transducer) or target resistance (in the case of amagneto-resistive type of transducer). The lapping process is alsotypically controlled so that the lower end or tip (such as the pole tipin a magnetic transducer) of each transducer 210 has a desired verticalposition relative to a reference on the slider body, such as bearingsurface 200.

The bearing features are then formed into the bearing surface 220 ofeach slider body 110, and each bar 208 is diced along a plurality ofdice lanes 228 into a plurality individual slider bodies 110.Alternatively, the bearing features can be formed on a slider level,after bars 208 have been diced into individual slider bodies.

Following the formation of each slider body, the lower tip of thetransducer is typically recessed from the bearing surface. Thisrecession is typically referred to as “pole tip recession”. While avariety of different types of transducers can be used, the term “poletip recession” is used herein to refer to recession of the lower tip ofthe transducer or other active element, even if the transducer does nothave a magnetic “pole”.

FIG. 4 schematically illustrates pole tip recession on one of thesliders 110. Following fabrication, as discussed above with reference toFIGS. 2 and 3, slider 110 includes a slider body or substrate 230 and aplurality of thin film layers 240 in which transducer 210 is fabricated.The slider 110 is then mounted to a suspension 112, which supports theslider over the surface of disc 107.

As disc 107 rotates, the surface of the disc has a tangential velocity250 relative to slider 110. Slider 110 flies with a positive pitch suchthat leading surface 226 flies at a greater distance from the surface ofdisc 107 than trailing surface 224. Transducer 210 is thereforetypically positioned along trailing surface 224 such that the lower tipof the transducer is positioned near the closest point on slider 110 tothe surface of disc 107. This position achieves the greatest resolutionbetween magnetic domains on disc 107.

The operating performance of transducer 210 is based in part on thespacing 254 between the lower tip of the transducer and the surface ofdisc 107. Spacing 254 is referred to as the head-media spacing (HMS).The head-media spacing 254 is based on tangential velocity 250 of disc107, the properties of suspension 112, the flying characteristics ofslider 110 and the vertical position of the pole tip on slider 110. Twoprimary factors contribute to the vertical position of the pole tip. Thefirst is pole tip recession 256 in which the vertical position of thepole tip becomes recessed (or protruded) relative to bearing surface 220due to the machining and other fabrication processes of the slider andtransducer structures. Manufacturing variations in pole tip recession256 can contribute to undesirable variation in head-media spacing, whichcan limit recording density. The second is thermal pole tip protrusion(TPTP), which is caused by increases in the environmental temperature ofthe product and by heat generated by write current through thetransducer during normal operation.

In one embodiment of the present invention, a structure is fabricated aspart of the plurality of thin film layers 240 on the wafer level, whichhas material stresses that can be treated on a slider level so as toadjust the pole tip position. The pre-stressed structure can be anactive element associated with operation of the transducer structure oran inactive element not associated with operation of the transducerstructure.

FIG. 5 is a fragmentary, trailing end view of slider 110, whichillustrates the addition of a pre-stressed structure 300 along trailingsurface 224 according to one embodiment of the present invention. Thematerial used for pre-stressed structure 300 and the optimization of thewafer-level processes are chosen such that structure 300 has a materialstress following fabrication, which is large enough to allow forsufficient adjustment of the pole tip recession at the slide level.

In FIG. 5, pre-stressed structure 300 is shown as being rectangular forillustration purposes only. Structure 300 can have any shape that can bepotentially advantageous to subsequent material stress treatment. Inthis embodiment, pre-stressed structure 300 is located on trailingsurface 224, between transducer structure 210 and back surface 222.However, pre-stressed structure 300 can be positioned at other locationson trailing surface 224 in alternative embodiments of the presentinvention.

FIG. 6 is a cross-sectional view of slider 110 taken along lines 6-6 ofFIG. 5 according to one embodiment of the present invention.Pre-stressed structure 300 is formed as one or more of the plurality oflayers 240 that form transducer 210. In this example, transducer 210 isa thin film magnetic transducer having a coil 400, a core 402, aninsulator 404, a pole tip 406, and an overcoat 408. Each of theseelements can be fabricated in one or more of the plurality of thin filmlayers 240 through a series of deposition, etching, lift-off-processesat the wafer level, for example. In this example, pre-stressed structure300 is formed beneath part of the outermost overcoat layer 408. Inalternative embodiments, pre-stressed structure 300 can be formed inother relative positions, such in the outermost layer, a layer that ispart of a transducer element, or a layer that is between two or moretransducer elements. Other types of transducers can also be used, suchas optical, magneto-optical, magneto-resistive, ferro-electric, etc.Also, transducer 210 can be configured for longitudinal or verticalrecording.

The method of stress treatment can be any one that modifies the materialstress in pre-stressed structure 300. One example of stress treatments,pre-stressed structure 300 is thermally relaxed to reduced compressivestress in the pre-stress structure. Other examples include any method ofremoving stressed material or machining the surface of structure 300 tomodify the surface stress. Pre-stressed structure 300 can be thermallyrelaxed by laser heat treatment, for example. Laser heat treatment canbe controlled to cause the material to shrink upon cooling. Therefore,an initial pole tip protrusion may be desired to achieve a final targetpole tip recession following laser heat treatment. However, any thermalheat treatment can be used.

Thermal heat treatment operates through two mechanisms. The firstmechanism is residual stress relaxation. During the wafer fabricationprocess, the transducer and pre-stressed structure are fabricatedthrough the sequential application and processing of thin film layers.During the fabrication process, the layers experience varioustemperature changes, including cooling after the final layer has beenapplied. The material forming the different layers can have differentthermal coefficients of expansion than one or more of the adjacentlayers. Therefore, any given layer, including those that form thepre-stressed structure 300, can become constrained by surroundingmaterials due to the temperature changes following each fabrication stepand the differing thermal coefficients of expansion. This results in alevel of material stress after the wafer has been fabricated.

Later, when the material in pre-stressed structure 300 is thermallytreated, such as with a laser, the material stress in structure 300 isrelieved, resulting in deformation in one or more of the thin filmlayers 240 and movement of transducer structure 210. Arrow 310represents vertical movement of transducer structure 210 relative tobearing surface 220 due to relaxation of residual material stress inpre-stressed structure 300.

The second mechanism is material re-solidification. When the laser beamscans over the material surface, the heating effect on the material canbe localized at or close to the material surface. The heating effect canbe so high that it can melt or even evaporate the material in thevicinity of the laser beam. For example, the temperature can be as highas 3000C at the beam center. After the laser beam is removed, the meltedmaterial re-solidifies, resulting in very high tensile stress in thelocal area. High intensity flux of the laser beam energy can result inhigh surface temperatures and steep temperature gradients in the treatedmaterial, which yields high cooling rates and in turn increases themagnitude of the residual tensile stresses in the material. For example,the resulting tensile stresses can be as high as 250 Mpa in somematerials. The residual tensile stress can be controlled to effectfurther vertical movement of the pole tips.

FIG. 7 is a diagram of an apparatus 500 for adjusting the recession ofthe pole tip (or other active element) of a transducer toward a desiredvertical position, according to one embodiment of the present invention.Apparatus 500 includes a recession measuring device 501, a thermalsource 502, a processing device, such as programmed computer, 504 andscanner 506. Programmed computer 504 operates measuring device 501,thermal source 502, and scanner 506 according to a sequence ofinstructions stored in a memory (not shown), which is associated withthe computer, and user commands provided by a user through a userinterface (also not shown). Computer 504 can include a single device ormultiple devices connected to the appropriate elements in apparatus 500.

During the recession adjustment process, each slider 110 is sequentiallymoved into a working position relative to beam 510 and measuring device501. The sequence of instructions, when executed by computer 504, causesapparatus 500 to measure the pole tip recession 256 (shown in FIG. 3)with measuring device 501, select appropriate operating parameters forthermal source 502 and scanner 506, and then alter the material stressesin pre-stressed structure 300.

In one embodiment, measuring device 501 includes an opticalinterferometer. Other measuring devices can also be used. Thermal source502 can include a laser, for example, which generates coherent lighthaving continuous or pulsed power that is delivered to scanner 506 overa fiber-optic cable 508. Fiber-optic cable 508 is coupled to scanner 506through a system of lenses 509, for example. Scanner 506 focuses thelight beam on pre-stressed structure 300 through an objective lens. Inone embodiment, scanner 506 includes a two-axis galvanometer with a setof mirrors that allow planar x-y motion of the focused beam 510 alongthe trailing surface of slider 110. Other optical elements can be usedin alternative embodiments.

As beam 510 is scanned along pre-stressed structure 300, the laser beammelts the surface material along the scan line, which reducespreexisting compressive stresses along the scan line. When the moltenmaterial solidifies, new tensile stress is added to the surfacematerial, depending on the operating parameters of the light beam. Theresulting stress change causes deformation of one or more layers alongtrailing surface 224. Thus, thermal treatment on pre-stressed structure300 can be used to cause a controlled change in the vertical position ofthe active elements of transducer 210 relative to bearing surface 220.The wavelength of beam 510 is preferably near the infrared region andprovides for enough heating to melt the material without materialremoval. With a continuous wave laser beam, the tensile stress inducedduring cooling of the substrate material is aligned predominantlyparallel to the scan direction. However, other light operatingparameters can also be used to alter material stresses in or onstructure 300 to effect a change in the vertical position of thetransducer.

Several factors can be used to control or optimize the residual stresslevel. Laser characteristics such as the laser operating mode and thelaser media can interact differently with different materials, resultingin different thermal stress-releasing behaviors and hence differentamounts of pole tip adjustment. For example, the laser can be operatedin the continuous wave mode or the pulsed mode, as mentioned above.Various laser media can be used such as a CO₂ laser, an Nd-YAG laser, ora Cu-Excimer laser, depending on the material used for pre-stressedstructure 300.

The laser power and scanning speed can be optimized as desired. Thelaser power affects the amount of stress-release within the material.The scanning speed affects homogenization. The laser power can be set tomelt and/or evaporate the material. The combination of the laser powerlevel and the scanning speed can be an effective input for controllingthe material response to the laser beam. Further, the pattern of laserscan lines on the material can affect the level and direction ofmaterial stress-release and the amount and direction of added tensilestress. For example, the number, location, density and orientation ofthe scan lines can be selected as desired.

The laser focus size can be used to control the Heat-Affected-Zone inthe material. The surface roughness of the pre-stressed material and anysurface coatings over the pre-stressed material can be used to changethe reflectivity and the absorptivity of the laser beam energy. Forexample, a typical material that is used for overcoat layer 408 (shownin FIG. 5) is alumina (Al₂O₃), which is largely transparent to the laserbeam. Other operating parameters can also be used for controlling theamount of pole tip adjustment.

A 1.0-1.5 KW CO₂ continuous wave laser has been reported in literatureto create a tensile stress level as high as 250 MPa on the surface of aniron-based material, wherein the scanning speed was 15-21 mm/s, and adefocus of about 22 mm out of a 137 mm laser focus length. Currentcommercial laser machines can easily provide power levels between 1W to10,000W. If a higher stress level is desirable, the power level can befurther increased within the range of the laser.

FIG. 8 is a flow chart illustrating a sequence of steps for adjustingrecession of a pole tip (or other active element) of a transduceraccording to one embodiment of the present invention. At step 701 anincoming slider is received for adjustment. The initial pole tiprecession is measured by measuring device 501 (shown in FIG. 6) at step702. Based on the measurement, computer 504 determines the laseradjustment parameters, at step 703, based on predetermined pole tiprecession (FM) response transfer functions 713 and a pre-determineddecision-making system. Some of the variables that can be controlled arediscussed above, and can include laser power 710, the number of scanlines 711, and the scan velocity 712. At step 704, a first lasertreatment is applied according to the parameters determined at step 703.A second pole tip recession measurement is made at step 705. If needed,a second set of process parameters can be determined at step 706 and asecond, refined laser treatment can be performed at step 707. A finalpole tip recession measurement is made at step 708. Any number ofmeasurement and laser treatment cycles can be used in alternativeembodiments of the present invention.

Computer modeling was conducted to test the transducer recessionresponse due to laser heat treatment. FIG. 9 is a graph illustrating thedeformed shapes along the bearing surface of slider 110 following asimulated laser heat treatment for various materials used for thepre-stressed structure 300. The x-axis represent location in microns(um) along the bearing surface, from the leading edge to the trailingedge, and the y-axis represents deformation in microinches (uin). Astructural temperature loading condition was used as a way of simulatingthe residual compressive stress in pre-stressed structure 300 followingfabrication at the wafer level. The assumed temperature change followingfabrication at the wafer level was −100C for all tested materials. FIG.10 is a chart illustrating normalized pole tip recession response due tothe simulated laser heat treatment for the various materials shown inFIG. 9. The various materials are plotted along the x-axis. The y-axisrepresents the normalized pole tip recession change in microinches permegapascal (MPa).

Looking at FIGS. 8 and 9, aluminum and zirconium are among thosematerials yielding the largest response. The materials that have thegreatest response to laser heat treatment are preferred. However, otherfactors such as compatibility with the transducer functionality andexisting processes and opacity of the material (related to laser energyabsorption), should also be considered when selecting the material to beused for the pre-stressed structure.

Based on the data shown in FIGS. 8 and 9, literature of laser treatmentand finite element modeling results, it is expected that relaxation of150 MPa compressive stress can yield up to 0.023 microinches in pole tiprecession adjustment. An additional laser-induced tensile stress of 200MPa can yield up to 0.031 microinches in pole tip recession adjustment,for a total adjustment of 0.054 microinches in one embodiment of thepresent invention. It is predicted that the pole tip recessionadjustment can be as high as 0.078 microinches, for example, if highercompressive and tensile stress are achieved in the wafer fabricationprocesses and the laser heat treatment. The material testing data andmodeling results predict that the maximum pole tip recession adjustmentcan be as high as two to three times the current pole tip recessionstandard deviation. With this amount of adjustment potential, theprocess described above is capable of fine-tuning pole tip recession ona slider-by-slider basis for greatly reducing variation from one sliderto the next.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the present invention have been setforth in the foregoing description, together with details of thestructure and function of various embodiments of the invention, thisdisclosure is illustrative only, and changes may be made in details,especially in matters of structure and arrangement of parts within theprinciples of the present invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed. For example, material stresses can be altered in thepre-stressed structure based on a heating process, a mechanical processor a material removal process, for example, in alternative embodimentsof the present invention. Also, the term “pole tip recession” is ageneric term intended to refer to recession of any active element of atransducer, wherein the vertical position of the element has an effecton the read and/or write performance of the transducer. The element isnot required to be a magnetic pole. The embodiments of the presentinvention can be applied to any surface on a substrate that carries atransducer. In addition, the present invention is not limited to datastorage systems.

1. A method of adjusting recession of an element in a transducerstructure formed in a plurality of thin film layers on an edge of aslider, the method comprising: (a) forming a pre-stressed structure aspart of the plurality of thin film layers on the edge of the slider,which has a level of material stress; (b) measuring the recession of theelement relative to a bearing surface of the slider; and (c) adjustingthe level of material stress as a function of the recession measured in(b) to effect a corresponding change in the recession.
 2. The method ofclaim 1 wherein (a) comprises forming the pre-stressed structure with amaterial having a different thermal coefficient of expansion than anadjacent one of the plurality of thin film layers, which is in contactwith the pre-stressed structure.
 3. The method of claim 1 wherein theslider comprises a back surface, which is opposite to the bearingsurface, the edge extends between the bearing surface and the backsurface, and (a) comprises forming the pre-stressed structure along theedge, between the transducer structure and the back surface.
 4. Themethod of claim 1 wherein (a) comprises forming the pre-stressedstructure as an outermost layer of the plurality of thin film layers. 5.The method of claim 1 wherein the plurality of thin film layerscomprises an outermost overcoat layer and wherein (a) comprises formingthe pre-stressed structure beneath the outermost overcoat layer.
 6. Themethod of claim 1 wherein the pre-stressed structure is an activeelement associated with operation of the transducer structure.
 7. Themethod of claim 1 wherein the pre-stressed structure is an inactiveelement not associated with operation of the transducer structure. 8.The method of claim 1 wherein (c) comprises thermally relaxing thepre-stressed structure to reduce compressive stress in the pre-stressedstructure.
 9. The method of claim 8 wherein (c) further comprises addingtensile stress to the pre-stressed structure.
 10. The method of claim 1and further comprising: (d) forming a wafer comprising a slidersubstrate material; (e) applying the plurality of thin film layers andthe pre-stressed structure to an active surface of the wafer; (f)slicing the wafer into a plurality of bars, each bar comprising aplurality of individual sliders and two opposite sliced surfaces; (g)separating the individual sliders such that, for each individual slider,the opposite sliced surfaces form the bearing surface and a backsurface, respectively, of the slider, and the active surface of thewafer forms the edge of the slider, which is adjacent to the bearingsurface; and (h) measuring the recession in (b) and adjusting the levelof material stress in (c) after separating the individual sliders in(g).
 11. A method of adjusting recession of an element in a transducerstructure formed in a plurality of thin film layers on an edge of aslider, the method comprising: (a) forming a pre-stressed structure aspart of the plurality of thin film layers on the edge of the slider,wherein the pre-stressed structure comprises a material having adifferent thermal coefficient of expansion than an adjacent one of theplurality of thin film layers, which is in contact with the pre-stressedstructure such that the material has a level of material stress; (b)measuring the recession of the element relative to a bearing surface ofthe slider; and (c) adjusting the level of material stress as a functionof the recession measured in (b) to effect a corresponding change in therecession.
 12. The method of claim 11 wherein the slider comprises aback surface, which is opposite to the bearing surface, the edge extendsbetween the bearing surface and the back surface, and (a) comprisesforming the pre-stressed structure along the edge, between thetransducer structure and the back surface.
 13. The method of claim 11wherein (a) comprises forming the pre-stressed structure as an outermostlayer of the plurality of thin film layers.
 14. The method of claim 11wherein the plurality of thin film layers comprises an outermostovercoat layer and wherein (a) comprises forming the pre-stressedstructure beneath the outermost overcoat layer.
 15. The method of claim11 wherein the pre-stressed structure is an active element associatedwith operation of the transducer structure.
 16. The method of claim 1wherein the pre-stressed structure is an inactive element not associatedwith operation of the transducer structure.
 17. The method of claim 1wherein (c) comprises thermally relaxing the pre-stressed structure toreduce compressive stress in the pre-stressed structure.
 18. The methodof claim 17 wherein (c) further comprises adding tensile stress to thepre-stressed structure.
 19. The method of claim 1 and furthercomprising: (d) forming a wafer comprising a slider substrate material;(e) applying the plurality of thin film layers and the pre-stressedstructure to an active surface of the wafer; (f) slicing the wafer intoa plurality of bars, each bar comprising a plurality of individualsliders and two opposite sliced surfaces; (g) separating the individualsliders such that, for each individual slider, the opposite slicedsurfaces form the bearing surface and a back surface, respectively, ofthe slider, and the active surface of the wafer forms the edge of theslider, which is adjacent to the bearing surface; and (h) measuring therecession in (b) and adjusting the level of material stress in (c) afterseparating the individual sliders in (g).
 20. A slider comprising: aslider body having a bearing surface, a back surface, which is oppositeto the bearing surface and an edge, which extends between the bearingsurface and the back surface; a transducer structure formed in aplurality of thin film layers on the edge of the slider and having anelement with a vertical position relative to the bearing surface; and aposition adjustment structure formed as part of the plurality of thinfilm layers and comprising a material having a different thermalcoefficient of expansion than an adjacent one of the plurality of thinfilm layers, which is in contact with the position adjustment structure,such that the material has a level of material stress, wherein theposition adjustment structure has a material stress adjustment patternthat is a function of the vertical position.
 21. The slider of claim 20wherein the position adjustment structure is located along the edge,between the transducer structure and the back surface.
 22. The slider ofclaim 20 wherein the position adjustment structure is formed as anoutermost layer of the plurality of thin film layers.
 23. The slider ofclaim 20 wherein the plurality of thin film layers comprises anoutermost overcoat layer and wherein the position adjustment structureis located beneath the outermost layer.
 24. The slider of claim 20wherein the position adjustment structure is an active elementassociated with operation of the transducer structure.
 25. The slider ofclaim 20 wherein the position adjustment structure is an inactiveelement not associated with operation of the transducer structure.